The underlined portion of the sentence needs to align with what it describes, the "scientists." To make it grammatically correct, the verb form of "debating" needs to be changed to a simple present form. "Still debate" is the correct answer choice.

The use of "making," a participle means the sentence has no verb, as a participle needs some form of "to be" to function as a full verb; therefore, a complete verb form needs to be used, and has to match the past tense usage of "tried." This makes the correct answer choice "made mistakes."

The use of the patriciple form "having" is incorrect in the sentence, as the participle cannot stand on its own as the verb of the sentence. The word needs to be changed, and must match the later use of the past tense construction "that they could not." The correct answer, therefore, is "the man had issues."

The use of "telling" in the sentence is strange and confusing, as the participle form appears to modify "ready." To appropriately explain what the father was "ready" for, an infinitive, which gives a sense of action; therefore, the correct answer choice is "to tell a joke."

The use of the present tense verb "reveal" is confusing in the sentence, as it essentially would act as a second verb in the sentence. The verb needs to be changed to a form that can function as a non-verb. The only answer choice that does this is "revealing their feelings," which uses the gerundive form.

The use of "having grown" in the sentence actually makes the sentence not have a verb, because the use of that verb creates a verbal phrase.  The sentence needs the phrase "having grown" to be turned into an actual verb. Therefore, the correct answer choice is "Politicians have grown increasingly aware."

Whlie one might say that something "was targeted," one cannot say that something "was targeted" something else and be grammatically correct. As only "targeted" is underlined, and not "was," it needs to be changed. Of all the answer choices, only "specifically targeting people" corrects the sentence's error without introducing new errors or extraneous words.

The use of "keeping" in the sentence is incorrect, as "keeping" needs some version of the verb "to be" to form a functioning verb. (In the phrase "the soldiers keeping watch," "keeping" is a participle.) The verb must be changed to a form that can work in the sentence. The only choice that does this and keeps the intended meaning is "The soldiers keep watch."

The use of the participle "holding" means that there is no actual verb in the sentence. Not only does the form have to change, but the use of "came" later in the sentence means the verb form needs to be the past tense. "The tiny force held down the fort" is the only answer choice that uses the correct tense.

The use of the participle "obsessing" actually makes the sentence have no verb, as a participle cannot stand as a verb without some form of the verb "to be." "Obsessing" needs to be changed to an appropriate verb form to make the sentence complete. The only answer choice that uses a correct verb form is "The athlete obsessed over."